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When tiling masks, sometimes we get tiles that are completely outside
the layer's visible rect. This would lead to problems in determining
whether quad rect contains visible rect, because an empty rect's origin
is not always contained by a quad rect that locates at a random origin.

This would result in problems when converting draw quads to RPDQs in
IPC, thus breaking Android WebView.

This CL makes RenderSurfaceImpl::TileMaskLayer throw away such quads.

Bug: 740810
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I07c4024894740d09ba4708d5ead37a4bec99d7ea
Reviewed-on: https://chromium-review.googlesource.com/570630Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Xianda Sun <sunxd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491082}